nice article explaining each term, but also look at other articles on similar subjects, particularly the one called Create a Living Will and Health Care Power of Attorney in Your State. Each state handles these issues differently, and Nolo provides an easy way to find out what your state requires.
Beware the link pointing you to buy software. Choosing to buy or download is certainly an option, but before you shell out some cash, check with your local library and see if they have the Nolo books with forms inside. You can make photocopies and fill in the information yourself. Also try a Google search for your state's law library and see if someone there can point you to free forms. The law librarian should also be able to direct you to more information specific to your state.